Fans of the smash-hit costume drama barely have recovered from the untimely demises of Lady Sybil (Jessica Brown Findlay) and Matthew Crawley (Dan Stevens) in season three, and now comes word that Siobhan Finneran -- who has played the scheming maid O'Brien since the show's beginning -- has had enough of the character.

“I’m not doing any more," the 47-year-old actress tells The Mirror. "O’Brien is a thoroughly despicable human being -- that was great to play."

A rep for the series confirms to The Hollywood Reporter, "O'Brien is leaving to do something else, but the door for her character is open."

Series creator Julian Fellowesrecently toldThe New York Times: “When an actor playing a servant wants to leave, there isn’t really a problem -- [he or she just] gets another job. … With members of the family, once they're not prepared to come back for any episodes at all, then it means death."